Tubular element for tubular steam generators



Jan. 26, 1960 w. HULSSE 2,922,405

TUBULAR ELEMENT FOR TUBULAR STEAM GENERATORS Filed April 29. 1955 2 Sheets-Sheet 1 INVENTOR.

BY WER/VER HLssE ArroR/vEr Jan. 26, 1960 w. HULssE 2,922,405

TUBULAR ELEMENT FOR TUBULAR STEAM GENERATORS Filed April 29, 1955 v2 Sheets-Sheet 2 Fig- 4- Fig- E.

Fig'. E.

INVENTOR.

WERNER H/.sss

ATTORNEY United States Patent G TUBULAR ELEMENT FOR TUBULAR STEAM GENERATORS Werner Hlsse, Gummersbach, Rhineland, Germany, as-

signor to Heinrich Vorkauf, Berlin-Schmargendorf, Germany Application April 29, 1955, Serial No. 504,898

Claims priority, application Germany March 30, 1950 11 Claims. (Cl. 122-406) The invention relates to a tubular element for tubular steam generators, and more particularly to an element consisting of a plurality of parallel tubes which extend vertically throughout the whole or at least the major part of their length and which are located the one in the rear of another in the current of the combustion gases of a furnace.

In conventional heated tubular elements consisting of a plurality of tubes, it frequently occurs that the least heated tubes, owing to an insufficient generation of steam, particularly under partial load, turn into down pipes, that means,'that the flow in these tubes reverses its direction from upwards to downwards. It is possible that the force of the water, which otherwise takes the generated steam bubbles along, becomes insui'lcient for that purpose with the result that the steam bubbles adhere to the walls of the tubes and thus are the cause of damage to the latter. This instability of the water circulation prevails even if the tubes are vertically arranged.

It is an object of the present invention to avoid the mentioned drawback and to provide means for stabilizing the water circulation and to equalize at least approximately the unequal heating of the tubes by the combustion gases.

Another object of the invention is the provision of a bank of tubes having a single radiated pipe connected therewith in series so that the pipe located at a furnace wall precedes the tubes of the bank in the direction of flow of the operating medium.

The invention further aims so to connect the mentioned pipe to the bank of tubes that the weakly heated, most rearwardly located tubes of the bank are nearest that pipe.

A device according to the invention oifers the advantage that, owing to the generation of steam in the single pipe, the water circulation will be stabilized, that,fur

thermore, the steam from the single pipe ows o predominantly through the weakly heated rear tubes of the bank, and that on account thereof, the heating of the tubes will be approximately equalized.

Further objects and details of the invention will be apparent from the description given hereinafter and the accompanying drawing illustrating several embodiments thereof by way of example.

In the drawing:

Fig. 1 is a longitudinal cross-section through a boiler provided with a tubular element according to the invention.

Fig. 2 is a cross-section along line 2 2 in Fig. l.

Figs. 3 and 4 are side elevations of modified elements, respectively.

Referring now to the drawing, the boiler illustrated in Figs. l and 2 is a water tube boiler in which all the walls of the furnace 11 are lined with cooling tubes. The tubes 12 at the front wall of the furnace 11 extend from a horizontal distributor 13 and open directly into the steam drum 14. The side wall tubes 15 extend from a. lowerdistributor 1 6 aud communicate with an upper collector 17 which at its left hand end is connected Vwith the drum 14 and at its right hand end with one of the return pipes18, provided in the rear corners of the furnace. The rear wall 34 of the furnace 11 is lined by vertical pipes 19, located in a plane transverse with respect to the boiler, the plane being indicated by the dash line P. These pipes 19 are connected with their lower ends to a distributor 35 which extends between the return pipes 18, and with their upper portions to parallel banks 20, respectively, each of which consists of several vertical tubes. The tubes of a bank are located the one in the rear of the other in a plane at right angles to the wall 34, i.e. parallel with respect to the current of the combustion gases indicated by arrows a. In consequence, the quantities of heat taken up by the individual tubes from the combustion gases differ; the first tube 21 will take up more heat than any one of the subsequent tubes. The last tube 22 will receive the least heat.

Means are provided to equalize, at least approximately, the different quantities of heat thus taken up by the tubes. For this purpose, the banks are arranged forward of the plane P, that means, the banks project forward into thefurnace space and each of the pipes 19 is so connected 'to its associated bank that the rearmost tube 22 of the bank is closest to the plane P in which the associated pipe 19 is located. In order to render this possible, the lirst vertical tube 21 of each bank has at its lower end an extension 31 which leads backward and downward to its connection with the upper end 32 of the associated pipe 19. However, it is, of course, also possible to form the extension 31 as a forwardly and upwardly directed portion of the pipe 19 to the end of which the lower end of the rst tube 21 is connected, ap'- proximately at 30. The lower ends of all the other tubes of the bank are connected to the extension 31. In con-` sequence, the steam water mixture generated inv pipe 19 will iow olf predominantly through the tubes nearest that pipe, that means, through tube 2 2 and the adjacent vertical tube or tubes of the bank. Hence, the distribu# tion of the steam water mixturefrom the pipes 19 will be such that the steam generation varying in the bank tubes will be approximately equalized, that means, about the same quantity of steam will ow through the first tube 21 as Vthrough the last tube 22. In all the tubes of a bank practically equal buoyancy will prevail owing to the arrangement according to the invention with the result that circulation'isensured at all loads.`

The verticaltubes of each bank 20 open intoy an associated upper connecting tube 23. "These connecting tubes constitute simultaneously the means for cooling the ceiling of the furnace 11'. VAt the one side they connect di? rectly withvthe drum 14, and at the other side they are connected to the transverse collector 24 thus the banks including their associated pipes 19 and connecting tubes 23 are separated from each other throughout their extension from the distributor 35 to the drum 14 and trans# verse collector 24. The transverse collector is also connected to the return pipes 18. Separation of the steam and Water of the mixture will oocur to a large extent in the horizontal collectors.17 and the collector 24 connected'to the return pipes 18. In order to convey the steam to the drum 14, the return pipes 18 are connected with the steam space of the drum by means of the tubes 25. The separated water ilows downward in the ,return pipes 18 and will be restored to the lower distributor 16. Water ows also to the distributor 16 through the 'down pipes 26 which extend from the water space of the drum. The down pipes 26 and return pipes 18 together with the lower distributors 16 and 35, the upper collectorsi17 and 24, and the steam .drum 14 constitute .an integral tu bular frame so that no special boiler frame is required to support the evaporation heating surface.

The combustion gases rise from the plain grate 27 into the .furnace 11. From theretheyzflowfbetween the levaporation` tubes of the banks of tubes 20, and thereafter through the heating surfaces .29 and 3.6 in l.the downwardly directed flue 28. Both Aheating surfaces may Vserve as feed water heaters, or, the heating surface 29 .may be formed asa superheater, .and only the heating surface 36 as afeed water heater.

The advantages have .been stated which follow from the connection of the rear wall pipes of the Afurnace with the banks of tubes if this connection is so made I.that the least heated tubes of ,the banks ,are located nearest the plane in which the associated rear Wall pipes 19 lie. A modification of the bank is shown in the embodiment according lto Fig. 3. :In lthis embodiment .the bank 40 comprises six tubes which ,extend vertically throughout the major ,portion .of their length. The lower portions of the rst tive ztubes 41 .are bent 90 at 42 so ,that their ends are .at vright angles .to the vertical .pipe 43 to which they are connected. The lower portion 45 v.of the sixth or rearmost tube 44 of the bank is bent crank-like soV that .it is in line with and fits into ,the upper end `of the pipe 43 which isa rear walllpipe of a furnace similar to the pipe 19 inFig. l. 'Ihe connection between the tube 44 .and the pipe 43 is vmade gas-.and-water-tight by means not shown. The upper ends .of the bank tubes 41 and 44 are connected to a horizontal :collector tube 47, `the function of which is similar ,to that .of ,the tube 23 in Fig. l. The ,pipe 43 as well ,as the tube 47 have `larger diameters than an individual one -of the bank tubesso that the'inner cross-section of pipe 43 and tube 47 is in accordance with the total inner cross-section of the bank tubes. lt will be clear that the major portion `of the steam-water mixture generated in the pine 43 will rather `continue its direction of flow indicated by theA arrow and 4enter lthe tube -44 than change its direction 90 and tlow off through the tubes 41. .Of these tubes again, the one adjacent the tube 44 will receive most of the remainder of the mixture as it is nearest the point where the roriginal low is somewhat blocked owingto the diameter of tube 44 being smaller than that of pipe 43.

In certain instances it is desirable that a superheater is located in an area having a temperature as high as possible because in such a case the temperature of the super-heated steam is subjected to thevleast uctuations when theload changes. A bank according to the invention can be readily modified as shown in Fig. 4 so that the foregoing requirement can be fulfilled. For this purpose, the tubes of the bank r are dividedinto two groups. One ofthe groups comprises the tubes 5:1 and 52 and the other ,group comprises the tubes 53, .54 .and 55. The two groups ,are distant so far from VAeach other that there is suticient space for a super-heater A56 indicated in dash lines in Fig. 4. If the groups arevspaced fairly far apart it is advisable to introduce the tubes of the front group, i.e. tubes 51 and 52, directly into the steam drum 14 and to connect the tubes 53, 54, 55, constituting the rear group, to an intermediate collector `57, from which the steam will be conveyed tothe drum through tube 58 and the water will be conducted to the heated tubular system through the transverse collector 24 and return pipes 18 in a manner and for a purpose as described with respect to the embodiment of Figs. 1 and 2. The lower ends of all vthe -tubes S1, 52, V53, 54 and S5 are directly lconnected `to a lforwardly and upwardly directed extension 61 of the `rear wall pipe 60. It will be noticed that in the three embodiments shown, the rearmost tube of each 4bank is llocated forward of and nearest to the rear wall pipe lto which it is connected, so that the entire bank is located within the furnace space 11.

It will be apparent to those skilled in the art that many modifications `:and alterations .of theistructureshown and described `can be made without departure from the spirit and essence of the invention`which, for this reason, shall not be limited but by the scope of the appended claims.

I claim:

1. In a tubular steam generator with a furnace having a rear wall extending part of the height of the furnace so as to leave an opening for the escape of the combustion gases from the furnace, the combination of said furnace with a plurality of parallel banks located side by side in said furnace and including each a plurality of parallel tubes vertical throughout at least the major portion of their length and located in the rear of one another and in one plane in and substantially parallel to the current of the combustion gases leaving Vsaid furnace through said escape opening and substantially adjacent said opening, collector means for each bank connected to the upper ends of said tubes of said bank to carry away a steam-water mixture generated in said tubes, a `transverse .distributor near the foot end of said rear wall, single upwardly directed pipes associated with said banks respectively, and `connected with their lower ends to said distributor, at least la portion of each pipe being substantially vertical, the vertical portions of all said pipes lining the rear wall of said furnace and being exposed to the heat thereof, vthe upper end .of said vertical portion of each pipe being connected in series with its associated Vbank so as to precede said bank in the direction of ilow of the operating medium from said distributor to said .collector means, the top end of 'said vertical portion ibeing closest to that one of the tubes of said bank which is rearmost in the direction of said combustion gas current, said banks including their associated single pipes being separated from each other throughout their .extension from said distributor :to said collector means.

2. A steam generator as claimed in claim l, said :banks of tubes being parallel to the side walls of said furnace and located near the rear end of the latter, and the rearmost 'tube of each bank being located slightly forward and higher than said vertical portion of its associated single pipe, so that said banks extend forward into the furnace space.

3. A steam generator as claimed in claim l, in which the inner diameter .of each single pipe is larger than the inner diameter of any tube of its associated bank.

4. A steam generator as claimed in claim l, wherein the length of said tubes of each bank increases from the one end of said bank to the other end.

5. A steam Vgenerator as claimed in claim l, the vertical portion of the foremost one of the tubes of each bank being shorter than the vertical portions of the other tubes of said bank, said `foremost tube including a downwardly and .rearwardly directed extension the end of which being connected to the upper end of the vertical portion of the associated single pipe, and the lower ends of said other tubes of said bank being connected to 'said extension.

6. A steam generator as claimed in claim l, each of said single Apipes including an extension adjoining the upper end of said vertical portion and projecting -in a forward and upward direction, the end of said extension being connected to the lower end of the .front tube of the associated bank, and the lower ends of said other tubes of said Vbank being ,connected to said extension.

7. A steam generator as claimed in claim l, the flower portion Vof the rearmost .tube .of each bank being `bent crank-like .and having a vertically directed end yin line with and connected to the upper end of said vertical :portion of the `associated single pipe, and the lower end portions ofthe other tubes of said bank being provided with a V90" :bend `connected with said .pipe underneath one another below said upper end of said pipe.

18. `A :steam `'generator as claimed in claim l, further comprising ya super-heater, said tubes of each of .said banks being fdivided Vinto .two lgroups spaced from veach other, and said super-heater being arranged in said space.

9. A steam generator as claimed in claim 1, further comprising a super-heater, said means for carrying away said steam-water mixture including a steam drum in the front and a collector tube in the rear of said furnace, said tubes of each of said banks being divided in a front group and a rear group spaced from said front group, said super-heater being arranged in said space between said groups, the upper ends of the tubes of said front groups being connected to said drum and the upper ends of the tubes of said rear group being connected to said collector tube.

10, In a tubular steam generator with a furnace having a rear wall extending part of the furnace height so as to leave an opening for the escape of the combustion gases, the combination of said furnace with a steam drum at its front end, a collector tube near the rear end of said furnace and extending transversely thereof, a steam carrying tube between said collector tube and the steam space of said drum, a transverse distributor near the foot end of said rear wall, a down pipe connected to said collector tube and said distributor tube, a plurality of parallel banks located side by side in parallel planes in said furnace and extending lengthwise thereof, each of said banks including a plurality of parallel tubes vertical throughout the major portion of their length and located in the rear of one another and in one plane in and substantially parallel to the current of the combustion gases leaving said furnace through said escape opening and substantially adjacent said opening, a connecting tube for each bank extending in the plane of said bank between said drum and said collector tube, the upper ends of the tubes of each bank being connected to the associated connecting tube, a plurality of single pipes as many as there are banks, at least a portion of each single pipe being vertical, said vertical portions lining the inside of the rear-wall of said furnace and extending upwards to said banks, the upper end of each of said vertical portions of said single pipes being connected in series with one of said banks so as to precede the as` sociated bank in the direction of ow of the operating medium and to be closest to that one of the tubes of said bank which is rearrnost in the direction of said combustion gas current, and the lowermost ends of said single pipes being connected to said distributor, said banks including their associated single pipes and associated connecting tubes being separated from each other through out their extension from said distributor to the ends of said connecting tubes.

11. A steam generator as claimed in claim 10 wherein said connecting tubes constitute ceiling tubes of said furnace, said banks extending from said ceiling tubes downward a portion of the height of said furnace into the latter, and said vertical portions of said single pipes extending from the lower end of said banks downwards to said distributor.

References Cited in the le of this patent UNITED STATES PATENTS 1,743,326 Davy Ian. 14, 1930 1,842,235 Barnes Jan. 19, 1932 2,252,061 Cassidy Aug. 12, 1941 2,403,237 Powell et al. July 2, 1946 FOREIGN PATENTS 695,844 Germany Sept. 4, 1940 352,390 Great Britain June 29, 1931 

